1. Field of the Invention
The invention relates to a two member child-resistant closure one member of which can be used separately as a closure which is not child-resistant.
2. Description of the Prior Art
Child-resistant closures have long been in use to prevent access by children to harmful substances, such as medicines, in containers closed by such closures. Governmental regulations require many substances to be packaged in child-resistant containers. Child-resistant closures typically require a particular complex set of manipulations to affect removal. A practical child-resistant closure is not only difficult or impossible for a child to remove, but is relatively easy for an adult user to remove.
Many prior designs of child-resistant closures have not met this last criterion. Some designs have required for their removal strength or dexterity beyond the capacity of some adult users, for example, the elderly or those afflicted with arthritis. Therefore, there have recently been proposed child-resistant closures which can be supplied by the pharmacist in a child-resistant mode, but which can be converted by the consumer for reuse without the child-resistant feature.
A convertible closure is described in U.S. Pat. Nos. 3,865,287, and Re. 29,779, both to Morris. Morris discloses a unitary reversible closure, having two independent positions of use for sealing a container, one of which is child-resistant, and the other of which is not child-resistant. No manipulation of the closure, other than its inversion, is necessary to reseal a container such that it is not child-resistant. Hence, there is the danger that some users would make this simple conversion without pausing to consider whether the child-resistant mode should be utilized instead. Moreover, the commercial embodiment of the Morris invention utilizes a resilient pawl as a child-resistant locking means. Such a design is not as child-resistant as tow piece closures.
An effective two piece child-resistant closure is disclosed in U.S. Pat. No. 4,059,198, to Mumford. It is possible to apply this closure without engaging the locking means, such that it is retained on a cooperating container by an interference fit only. However, in such a situation, the retention of the closure on the container is not secure. Moreover, there is no visual indication that the container and closure are not child-resistant.